The present invention relates to a pneumatic tire, especially a pneumatic vehicle tire, comprised of a carcass with reinforcing members and radially inwardly positioned beads and a profiled tread strip applied onto the carcass whereby onto the tread strip an additional layer for reinforcing the tread is applied.
The tread of such pneumatic tires should ensure as much as possible under any weather conditions optimal performance (driving properties) of the tire.
Tread strip compositions are known which are soft and can thus adapt easily to the road surface. Accordingly, the corresponding tread strips have a better traction on the road surface than tread strips made of a hard composition. During driving (i.e., rolling on the road surface) the soft tread blocks and/or tread grooves are bent and/or tilted so that the contact surface area of the tire tread in contact with the road surface is reduced.
With the prior art concepts this problem could not be solved sufficiently.
Known in the prior art are, for example, additional layers made of rubber which are applied to the tread surface of the green tire and are formed together with the green tire. Such additional layers are comprised of rubber mixtures that during vulcanization due to their viscous flow properties cover the flanks of the tread only partially and in thin layers in the main flow directions. For example, German Offenlegungsschrift 1 480 981 discloses an additional layer made of a hard and wear-resistant (abrasion-proof) mixture that is supposed to harden the upper edges of the tread blocks in order to cut into grease films (slippery coatings) on road surfaces. However, this embodiment does not result in a reinforcement of the entire tread block due to the aforementioned flow behavior of the rubber mixtures.
It is furthermore known to reinforce tread strip mixtures with short fibers of different materials such as rayon, polyester, polyamide, or aramide (German Gebrauchsmuster 1 900 114). A disadvantage of such mixtures is a very low wear resistance (abrasion resistance) of the tread surface.
In order to avoid these disadvantages, it is an object of the present invention to improve the performance of pneumatic tires, especially their traction, by effectively stabilizing the tread blocks and/or tread grooves.